Skin lightening composition comprising an extract of plants from the families of symplocos or rubia

ABSTRACT

A cosmetic skin lightening composition, comprising 0.1-50 % by weight of an extract of plants from the families of Symplocos, Rubia or a mixture thereof.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to an improved cosmetic composition fortopical application to human skin to provide enhanced protection fromsunlight. The invention particularly relates to a skin lighteningcomposition prepared from natural actives.

BACKGROUND OF THE PRIOR ART

Melanin is the black pigment synthesised by the action of the enzymetyrosinase on the amino acid tyrosine. The reaction takes place inorganelles called melanosomes contained within cells called melanocytes.Melanocytes transfer melanosomes with melanin to neighbouringkeratinocytes which harbour these organelles till they are themselvesshed from the body from the superficial layers of the skin. Theintensity of the skin colour is directly related to the number, thesize, melanin content, the rate of formation and transfer of melanosomesto keratinocytes and degradation of melanin in keratinocytes. Melanin isalso an important protectant of skin and tissues beneath the skin as ithas the capacity to absorb incident ultraviolet light.

The UV range is divided into three regions, UV-A, having a wavelength offrom about 320 to 400 nm which gives a tanning effect withoutinflammation; UV-B, having a wavelength of from about 290-320 nm whichis responsible for erythema (sunburn) and eventually for tanning; andUV-C, having a wavelength of from about 200-290 nm, normally absorbed bythe ozone layer in the earth's atmosphere, but which is potentially verydamaging to the skin.

Melanogenesis and pigmentation of the skin are closely related responsesto irradiation by UV light. Exposure to sunlight leads to darkening ofthe skin by immediate pigment darkening of already formed melanin, andalso by formation of new melanin. Many skin compositions are formulatedfor the purpose of maintaining the colour of the skin against darkeningfollowing exposure to ultra-violet light. These compositions have beenbased on materials which deflect and scatter incident ultra-violet lightof the wavelength which produce burning and tanning of the skin or whichabsorb this light.

Conventional skin lightening compositions are based on sunscreens orskin lightening agents. The latter are believed to control dispersion ofmelanosomes or inhibit tyrosinase. Sunscreens alone can not lighten theskin beyond the natural skin colour and their only action is to reducethe ingress of ambient ultraviolet radiation into the skin. Thus, theyexert their effect only during the day. Some of the compounds used asskin lightening agents are also known to have undesirable side effects.

Several cosmetic products formulated using plant parts are available inthe market. The advantages of plant source of actives in variouscosmetic preparations such as skin creams, shampoos, hair applications,perfumes, soothing and nourishing creams etc has been well established.Synthetic actives are considered to be harsher than similar activesobtained from natural sources such as plants.

US20030096023 discloses tyrosinase inhibitors obtained from severaldicotyledonous plant species thus leading to skin lightening. The plantsare those belonging to the family Polygonaceae, Rosaceae, andOnagraceae.

The present inventors have identified that plant extracts of the speciesbelonging to the genera Symplocos or Rubia on topical application to theskin give improved skin lightening benefits. It is possible to formulatecosmetic compositions incorporating the extracts from these plants toprovide protection from the UV damage caused by the sun's radiation andalso bring about lightening of the skin.

JP2001192317 (Shiseido) 2001, discloses matrix metalloproteinasesinhibitors from several plants including Symplocos. Such an inhibitionprovides benefit in preventing wrinkles, skin aging.

U.S. Pat. No. 6,258,344 (Procter, 2001), discloses skin lighteningcompositions having certain hydroquinone derivatives, and lists Rubiaunder the class of natural anti-inflammatory agents.

JP09175962 (Lion, 1997), discloses use of plants belonging to the familyof Rubia cordifolia, in a hair dyeing composition. This refers todarkening of hair which is contrary to the skin lightening effect.

JP2001163755 (Shiseido, 2001), discloses the use of Glycyrrhiza inpreparations for external use for skin to obtain skin bleaching effectand JP11021228 (Kanebo, 1999) discloses Glycyrrhiza as ananti-inflammatory agent.

U.S. Pat. No. 6,455,057 (Elizabeth Arden , 2002), discloses a skin carecomposition comprising petroselinic acid and/or derivatives thereof; aphenolic compound and/or mixtures thereof; and a dermatologicallyacceptable vehicle for treating wrinkles and soothing sensitive skin.However, they disclose coriander seed oil as a source of petroselinicacid.

However, none of the prior art teaches the skin lightening andprotection against damaging effects of ultraviolet radiation by usingthe extracts of Symplocos or Rubia and cosmetic compositions comprisingthem.

It is the object of the invention to provide a synergistic cosmeticcomposition comprising skin lightening actives selected from plantsources.

It is another object of the invention to provide a synergistic cosmeticcomposition that will provide protection against the damaging effects ofultra violet radiation by the use of actives from natural sources.

It is yet another object of the invention to provide a synergisticcosmetic composition that will provide skin lightening with outrequiring the use of chemical actives.

SUMMARY OF THE INVENTION

According to the present invention there is provided a cosmetic skinlightening composition comprising an extract of the plant Symplocos orRubia or a mixture thereof.

According to the preferred aspect of the present invention there isprovided a cosmetic skin lightening composition comprising 0.1-50% byweight of the composition an extract of the plant Symplocos or Rubia ora mixture thereof.

According to the preferred aspect of the present invention there isprovided a cosmetic skin lightening composition comprising:

-   -   i. 0.1-50% by weight of the composition an extract of the plant        Symplocos or Rubia or a mixture thereof;    -   ii. 0.1 to 10% by weight of a sunscreen.

The plant parts used in the composition may be selected from any part ofthe plant but preferably from the stem, bark, leaves, flowers, or roots.It is particularly preferred that the bark of the plant is used.

The extract is prepared using any suitable solvent andparticularly-preferred solvent is water.

DETAILED DESCRIPTION OF THE INVENTION

It is an essential aspect of the present invention that the plantextracts of Symplocos or Rubia are incorporated in the cosmeticcomposition. However, other plant extracts from Glycyrrhiza, Coriandum,Acorus and useful conventional ingredients may be added to thecomposition.

Symplocos, is a genus belonging to the family Symplocaceae, commonlyavailable in India. It has several species of which S. recemosa, S.paniculata and S. cochinchinensis are the preferred species for use inthe composition.

Rubia, is a genus belonging to the family Rubiaceae of which R.cordifolia, commonly available in India is the preferred species.

The conventional ingredients may be in the nature of sunscreens, otherskin lightening agents chosen from natural or other synthetic sources,moisturizers, humectants, benefit agents, perfumes etc.

The composition of the invention may optionally comprise from 0.1 to10%, preferably 0.5 to 5% by weight of one or more skin whiteningagents. The skin whitening agent is preferably chosen from niacin,niacinamide or a precursor thereof that is capable of releasingniacinamide on the skin. Niacinamide is the amide of niacin and is alsoknown as nicotinamide or pyridine-3-carboxylic acid. An example of acompound which is a niacinamide precursor is niacinamide ascorbate.Other suitable skin whitening agents include extracts of placenta,hydroquinone and derivatives (eg. arbutin), kojic acid, dicarboxylicacids (azelaic acid, sebacic acid), represented by the formulaHOOC—(C_(x)H_(y))—COOH where x=4 to 20 and y=6 to 40, ascorbic acid andderivatives thereof, hydroxy acids (lactic acid, glycolic acid, malicacid, tartaric acid etc), ferulic acid, retinol and derivatives or anyother known skin whitening compounds.

The sunscreens used may be organic or inorganic in nature and arepreferably chosen from 4-tertiary butyl-4′-methoxy dibenzoylmethane,available under the trade name PARSOL 1789 ex Givaudan, 2-ethyl hexylmethoxy cinnamate, available under the trade name PARSOL MCX ex Givaudanor mixtures of the two sunscreen compounds. The composition comprises0.1 to 10% by weight of the composition and preferably 0.1 to 5% byweight of the composition of a sunscreen compound. Inorganic sunscreensare for e.g. titanium dioxide, zinc oxide, and preferably in themicronized form.

The vehicle which forms part of the cosmetic composition is one or moresubstances which are mutually compatible with the sunscreen and ifpresent, the skin whitening agent, and does not harm the skin. Thevehicle can act as a diluent, dispersant or carrier for the otheringredients of the composition, and is therefore intended to ensure thatthey can be readily applied to and distributed evenly over the skin atan appropriate concentration.

The vehicles that can be used in compositions according to the inventioncan include water, powder absorbents, binders and carriers and liquidssuch as emollients, propellants, solvents, humectants and thickeners.

Examples of moisturisers and humectants include polyols, glycerol, cetylalcohol, carbopol 934, ethoxylated castor oil, paraffin oils, lanolinand its derivatives. Silicone compounds such as silicone surfactantslike DC3225C (Dow Corning) and/or silicone emollients, silicone oil(DC-200 Ex-Dow Corning) may also be included.

Compositions according to the invention can be prepared for topicalapplication to the skin in the form of conventional product types suchas creams, lotions, ointments and aerosol products.

The invention will now be illustrated by way of Examples. The Examplesare for illustration only and do not in any way restrict the scope ofthe invention.

EXAMPLES

In order to test the efficacy of an active in vitro three different cellbased assays were used. The herb extract was used as the active that wasprepared by the following procedure.

Herbs Tested:

The barks of Rubia cordifolia (A), and Symplocos racemosa (B), were usedin the different tests mentioned below.

Extraction Procedure of Herbs:

A 12.5% weight/Volume extract of the herbs was prepared in water. Thisextract was centrifuged at 14,000×g for 10 min, filtered through a 0.2micron filter, and 20 micro liter of stock/ml of cell culture media(=0.25% w/v) was used for all the cell culture assays.

i. In vitro Synthesis of Melanin:

The effect of the active on melanin synthesis was tested usingmelanocytes in culture. B16 melanocytes were grown in culture till theywere about 60-70% confluent. The active was then added to the media andthe cells were grown till they were confluent. The cells were thenharvested and their melanin content was measured at 400 nm using aspectrophotometer. The effect of the actives are presented as a percentof the melanin content of control cells (where the active was notprovided) in Table 1. TABLE 1 Melanin Content (% of control) TreatmentMean ± SEM A 131.5 B 89.1 A + B 95.1The data show that Rubia does not have an influence on the amount ofmelanin formed while Symplocos reduces the amount of melanin formed. Acombination of Rubia and Symplocos show a synergistic reduction in theamount of melanin formed.

ii. Melanin Uptake by Keratinocytes:

The effects of the active on melanin uptake by keratinocytes were testedusing HaCaT keratinocytes in culture. HaCaT keratinocytes were culturedtill they reached confluence. Cells were then switched to media with noserum and 25 micro gram of synthetic melanin was added to the cellsalong with the actives. After an overnight incubation, cells were washedand melanin content was measured using a spectrophotometer. The effectof the actives is presented as a percent of the melanin content ofcontrol cells in Table 2. TABLE 2 Melanin uptake (% of control)Treatment Mean ± SEM A 94.6 B 89.78 A + B 89.6The data show that both Rubia and Symplocos alone and in combinationdecreased the melanin uptake.

iii. Effect on Skin Lightening on a Human Panel:

Combinations of herbs comprising Rubia cordifolia and Symplocos racemosawere formulated into cosmetic creams whose formulation is presented intable 3 and tested on human volunteers in a short-term skin lighteningclinical. Untreated and Placebo cream without the herbal extract weremaintained for comparison and the results on skin lightening arepresented in table 4.

Specific sites were marked on the forearms of 15 volunteers for creamapplication. The initial skin colour reading on each site served asuntreated control. Study personnel applied 3 mg of cream on to each testsite. This process was repeated for a period of 10 days. On the 11^(th)day, the subjects were clinically evaluated and scored on a colour scaleof 1 to 10 where 1 is the lightest and 10 is the darkest. The datapresented in table 4 is the difference in skin colour before and aftertreatment. TABLE 3 Ingredients % w/w Glycerin 1.0 Potassium Hydroxide0.57 Herbal extract 30.0 Stearic acid 10.0 Cetyl Alcohol 0.6Preservatives 0.3 Silicon Oil 0.5 Water To 100

TABLE 4 Treatment Skin lightening Untreated 0 Placebo cream 0.29 Herbalcream 0.39The data show that the herbal extracts even when formulated into acosmetic composition showed significant skin lightening benefits.

Thus it is apparent from the above that it has been possible toformulate cosmetic compositions using extracts from plants to providesignificant skin lightening benefits.

1. A cosmetic skin lightening composition, comprising 0.1 -50% by weightof extracts of plants from the genera Symplocos and Rubia; the extractof Symplocos being selected from Symplocos recemosa, Symplocospaniculata, Symplocos cochinchinensis or mixtures thereof; the extractof Rubia being Rubia cordifolia.
 2. The cosmetic skin lighteningcomposition of claim 1, additionally comprising 0.1-10% by weight of asunscreen.
 3. The cosmetic skin lightening composition of claim 1,further comprising 0.1-10% by weight of one or more skin whiteningagents.
 4. The cosmetic skin lightening composition of claim 1, whereinthe extract of Symplocos is Symplocos recemosa.
 5. The cosmetic skinlightening composition of claim 1, wherein the sunscreen is selectedfrom 4-tertiary butyl-4′-methyoxy dibenzoylmethane, 2-ethyl hexylmethoxy cinnamate, micronized titanium dioxide, or micronized zincoxide.
 6. The cosmetic skin lightening composition of claim 3, whereinthe skin whitening agent is niacin, niacinamide or a pre thereof.
 7. Thecosmetic skin lightening composition of claim 1 further comprisingextracts of Glycyrrhiza, Coriandum, Acorus or mixture thereof.
 8. Thecosmetic skin lightening composition of claim 1 wherein the Symplocos orRubia is extracted from the bark of the plant.